# Full text of "Handbook Of Chemical Engineering - I"

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```THE TRANSPORTATION OF GASES
145
6 are constants varying with different gases (see p. 190 for a table of these constants). If a gas be expanded or compressed adiabatically (without gain or loss of heat from or to external objects), the equation is pxy — RmT, where 7 = 1.406 approximately.
Accompanying tables give the weight of a cubic foot of air at various temperatures and pressures (Table 1), the specific gravity of various other gases (Table 2), and the weight of saturated air per cubic foot (Table 3), together with other useful data concerning gases. Gas measurements are reduced for comparison to their calculated volume at 0°C. and 760 mm. Hg. pressure (29.92 in.) which are known as normal temperature and pressure (N. P. T.)
The critical temperature of a gas is such a temperature that above it, no pressure, however great, will liquefy the gas. The critical pressure is that pressure at which gas at the critical temperature begins to liquefy. (See Table 2, also p. 657 1
TABLE 3.—WEIGHT OF SATURATED AIR IN POUNDS PER CUBIC FOOT
BAROMETRIC PRESSURES
Temperature,	Barometer readings, inches of mercury
degrees Fahrenheit	28.5	29.0	29.5	29.7	29.9	30.1	30.3	30.5
30	0. 07703	0.07839	0. 07974	0.08028	0. 08083	0.08137	0.08191	0.08245
35	0.07621	0.07756	0. 07890	0.07943	0. 07997	0.08051	0.08104	0.08158
40	0.07541	0. 07674	0. 07806	0. 07859	0.07913	0. 07966	0.08019	0.08072
45	0.07461	0.07592	0. 07724	0.07776	0. 07829	0. 07881	0. 07934	0.07986
50	0.07381	0.07512	0. 07642	0.07694	0. 07746	0.07798	0.07850	0.07902
55	0.07302	0.07431	0.07560	0.07612	0. 07663	0.07715	0.07766	0.07818
60	0.07224	0.07352	0. 07479	0.07530	0.07581	0. 07632	0. 07683	0.07734
65	0.07145	0.07272	0. 07398	0.07449	0. 07499	0. 07550	0. 07600	0.07651
70	0.07067	0.07192	0.07317	0.07367	0. 07417	0.07467	0.07518	0.07568
75	0.06988	0.07112	0. 07236	0.07286	0. 07335	0. 07385	0. 07434	0.07484
80	0. 06909	0.07032	0.07155	0.07204	0. 07253	0.07302	0.07351	0.07400
85	0.06829	0.06950	0. 07072	0.07121	0.07170	0.07218	0. 07267	0.07316
90	0.06748	0.06868	0.06989	0.07037	0. 07085	0.07133	0.07182	0.07230
95	0.06665	0.06785	0. 06904	0.06592	0. 07000	0. 07048	0. 07095	0.07143
100	0.06581	0.06700	0.06818	0.06866	0.06913	0.06960	0. 07008	0.07055
0. 08381 0.08292 0.08205 0.08118 0.08032 0.07947 0.07862 0.07777 0.07693 0.07608 0.07523 0.07437 0.07351 0.07263 0.07174
Specific Heat.—The instantaneous specific heat of dry air is given by F. G. Swann as 0.24112 + 0.000009 t, and the specific heat of waiter vapor as 0.4423 + 0.00018 t, where t is the temperature in degrees Fahrenheit. The mean specific heat of air with any degree of saturation may then be found by multiplying the
TABLE 4.—SPECIFIC HEATS or DRY AND SATURATED AIR (COST. PRESS.)
Temperature, degrees Fahrenheit	Specific heat of		Temperature, degrees Fahrenheit	Specific heat of
Dry air	Saturated air .		Dry air	Saturated air
60	0.2417	0.244	85	0.2419	0.2474
65	0'2417	0.2447	90	0.2419	0.2486
70	0.2417	0.2452	95	0 . 2420	0.2498
75	0.2418	0.2458	100	0.2420	0.2512
80	0.2418	0.2466
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